Memory devices, such as floating gate flash memory and EPROM, are known in the art for storing data in a wide variety of electronic devices and applications. UV (Ultraviolet) erasable memory devices are fabricated with UV transparent interlayer dielectric (ILD) materials. By providing a UV transparent ILD, process induced charges, such as those stored in a gate dielectric of a memory cell, for example, can be erased during fabrication and prior to programming to avoid unwanted threshold voltage shift in the memory cells of a memory device.
Several drawbacks, however, are associated with conventional UV transparent ILD materials in memory devices. A significant drawback is that UV transparent ILD exposes its adjacent regions, e.g., gate dielectric, to potential unwanted charge created by other processes involving UV radiation during fabrication. Another drawback is that those same regions are also exposed to potential extrinsic damage, such as breaking of bonds in a gate dielectric, during other processes. Yet another drawback with UV transparent ILD is that such materials may have poor gap-filling performance, and thus use of UV transparent ILD creates structural shortcomings in the memory device. As the aspect ratios of gaps, i.e., the ratio of the height to the width of a gap, have increased in conjunction with devices becoming smaller, use of UV transparent ILD becomes even more problematic. Such drawbacks result in unreliable and/or poorly performing memory devices.
Accordingly, there exists a strong need in the art for a memory structure having a tunable interlayer dielectric and a method for fabricating the same.